Deperdussin Racing Monocoque 1913 (oz15217)

About this Plan

Deperdussin Racing Monocoque 1913. Free flight scale model for CO2 power. Scale is 1/20.

Quote: "A diminutive flying scale model for CO2 Power. Deperdussin, by Richard Halfpenny.

This type of 'Dep', as it was affectionately known, was one of a series of high-powered racing monoplanes, developed during 1912-13 by the Deperdussin Company, which had branches in England and France. One of these aircraft won the Gordon Bennett Trophy at Rheims in 1913, when it averaged 127 mph on a lap of a closed circuit. Maximum speed was believed to be at least 135 mph, making this, almost certainly, the fastest aeroplane in the world at the time: its only possible rivals were a Ponnier monoplane of equal power, and, amazingly enough, the Royal Aircraft Factory SE4 biplane.

The aircraft was described, in its time, as a 'racing monocoque', because its fuselage was of advanced moulded plywood construction. Power was by a huge 14 cylinder, double row Gnome rotary engine of 160 hp, and, as the machine had a wingspan of only 22 feet, it must, with the powerful torque from its engine, have been a considerable handful for the pilot. In fact, the wings of the record breaking aircraft were clipped, to less than 20 feet span, to further increase its speed.

Beautifully streamlined, and a credit to Deperdussin who were renowned for the attractive appearance of their aircraft, this monoplane was years ahead of its time, apart from the retrograde feature of having wings that warped for control. Paradoxically, these had to be lightly constructed for flexibility, and thus had to be extensively wire braced. It was to be many years before cantilever wings for monoplanes became practical.

Unfortunately, the Deperdussin Company became insolvent in 1913, but eventually was combined with the French SPAD concern, builders of famous fighter aircraft during the Great War. The only surviving Deperdussin known to the writer is an earlier one, of much lower power, belonging to the Shuttleworth Collection.

Model construction: Fuselage: The model is small, even by CO2 standards, being to 1/20th scale. But, it has very broad wings, and can be built lightly. The planked fuselage itself need weigh no more than half an ounce.

Cut the fuselage keel and formers from soft, light balsa, and mark their centre lines with a biro. Assemble with balsa cement, and lay the first plank, of 1/4 by 1/16 soft light balsa, along the centre line, cementing to the formers. It will act as a reference later. Holding with pins, or rubber bands where needed, plank the whole fuselage, tapering where necessary, and making the joints as close as possible. Sand well for lightness, and cut out the cockpit where shown. Remove the keel below it, almost to the bottom, with a fine saw blade. Build up headrest as shown, planking with narrow, tapered 1/16th strips. When this is sanded, apply wood stain to the whole (my own is mahogany), and when dry, coat with cellulose based sanding sealer, or banana oil. Sand smooth when dry, and apply more coats as needed. A good finish can be worked up, with very little added weight.

The firewall is of millimetre ply, with captive nuts for the 002 motor, looped with fuse wire, and super glued to its back. The engine mounting should be arranged so that, with about 4 degrees downthrust, and about 2 degrees right sidethrust, the airscrew boss comes about central. Small washers are used for thrust packing, and the firewall, which may be left oversize, and trimmed later, should be glued in place with PVA. Cut a 1/2 square hole in the bottom of the fuselage, behind the firewall, and one side of the keel, and glue the plywood plate for the filler nozzle oposite it, as shown, Make a slot through the keel to it, so that, when the gas tank is pushed up into place, the 002 tube, bent downwards, guides the nozzle into position..."

Supplementary file notes

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